A kumquat (from the Cantonese 柑橘 "Gam2 Gwat1"; the Pinyin rendering of the Mandarin word is "Gan1 Ju2") is a small fruit resembling an orange.
The kumquat tree is slow-growing, evergreen, and 2.5-4.5 metres tall. Kumquats originated in China (noted in literature there in the 12th century). Originally in the genus Citrus they were set apart in the genus Fortunella in 1915. Kumquats are members of the family Rutaceae. Current varieties include Hong Kong Wild (Fortunella hindsii), Marumi (Fortunella japonica), Meiwa (Fortunella crassifolia), and Nagami (Fortunella margarita). They are currently cultivated in China, South East Asia, Japan and the USA.
The fruits are also called kinkan. The fruit is related to the mandarin orange. In appearance it resembles an oval or oblong orange, 3 to 5 cm long and 2 to 4 cm wide. Depending on variety, peel ranges from yellow to red - a Nagami kumquat is oval and has a yellow skin, while a Marumi kumquat is round with an orange colored skin. Kumquats are frequently eaten whole - the skin is tart and the inner layer sweet (or vice-versa) and green. The variety of kumquat in Hong Kong has rather sweet rind compared to rind of other citrus fruits. The juicy center is often too sour to eat and is thrown away after the rind is consumed. The fruit is also candied and made into preserves, marmalade, and jelly.
Cantonese preserves kumquats in salt. A batch of the fruit is buried in dry salt inside a glass jar. Over time, all the juice from the fruit is extracted through osmosis into the salt. The fruits in the jar will become shrunken and wrinkled in dark brown color, and the salt will become a dark brown brine. A few salted kamquats and a few teaspoonful of the brined juice are mixed with hot water to make a remedy for sore throat. A jar of such preserved kumquats can last several years.